Prepackaged monopropellant gas generator buoyancy system

ABSTRACT

A prepackaged monopropellant gas generator buoyancy system having a variable lift capability wherein the effective volume of the lifting compartment may be variably adjusted by the user and incorporates a stainless steel bellows as the fuel compartment.

[5 6] References Cited UNITED STATES PATENTS 594,600 1 H1897 Chamberlain 9/8 3,471,877 10/1969 Bayles 9/8 3,512,493 5/ 1970 Hallanger 9/ 8 3,372,996 3/1968 Barrett et a1 4/53 X Primary Examiner-Trygve M. Blix Assistant Examiner-Gregory W. OConnor Attorneys-Edgar J. Brower and Roy Miller ABSTRACT: A prepackaged monopropellunt gas generator buoyancy system having a variable lift capability wherein the effective volume of the lifting compartment may be variably adjusted by the user and incorporates a stainless steel bellows as the fuel compartment.

maximum 41972 3631.551

SHEET 1 UF 3 lNVliN'l (JR. DONALD MILLER ROY MILLER ATTORNEY.

PREPACKAGED MONOPROPELLANT GAS GENERATOR BUOYANCY SYSTEM GOVERNMENT INTEREST BACKGROUND OF THE INVENTION Copending application Ser. No. 783,974, filed Dec. I6, 1968 titled Self-contained Underwater Buoyancy System by Donald Miller describes a buoyancy system which may be controlled and used at various depths. Although the system operates satisfactorily, problems may occur during the fueling operation as follows: 1 fuel spillage caused by the movement of the ship, (2) open flames produced by welding and smoking, (3) exposure of personnel to fuel vapors and (4) disposal of residual fuel. The fuel used, hydrazine, is a toxic flammable material which may produce harmful effects due to ingestion, inhalation of vapors or contact with the skin.

In order to make the buoyancy system a useful tool for the salvage diver, the salvage support personnel must be trained to handle hydrazine fuel or a system must be provided in which no physical contact is made with the hydrazine fuel once the containers are put aboard the salvage ship. Solution of the latter alternative resulted in a development of a hydrazine expulsion bellows fuel element ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross section ofthe fuel expulsion unit;

FIG. 2 is a cross section of the fuel expulsion unit in a loaded condition; and

FIG. 3 is a partial cross section of an all-up unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT The fuel expulsion unit prior to loading of the fuel is shown in FIG. 1 wherein hollow cylindrical expulsion unit contains therein a spring 11 one end of which engages a piston member 12 the other side of which in unloaded condition engages the inner surface of bellows container plate 13. The other end of spring 11 engages the inner surface of end plate 14.

In loading the expulsion unit 10 a loading screw 15 threadedly engages loading plate 16. One end of the loading screw 15 is formed in the shape of a key as at 17 which engages a keyway 18 in the piston member 12. The loading screw 15 is rotated, drawing piston member 12 toward end plate 14 until the spring I1 is in compressed form.

At this point, see FIG. 2, a hydrazine expulsion bellows fuel element 35 is inserted into the empty space by removing ofthe bellows retainer plate 13. Affixed to one end ofthe bellows expulsion unit is the male half ofa quick disconnect.

FIG. 3 illustrates, partly in cross section, an all-up configuration ofthe buoyancy system wherein are shown end portions 20 and 21 formed ofa foam. Molded over the end portions are pressure hemispheres 22 and 23, respectively, formed of Fiberglas. Fiberglas portion 23 extends over the end portion 21 to form a right cylinder section which is hollow in its interior. The section 23 is secured to end portion 22 by means of clips 24, one of which is shown. Attached to the end portions 20 and 21 are lifting eyes 25 and 26, respectively, for attaching lines thereto. In addition, the fuel expulsion unit 10 is secured to the end portion 20.

Attached to the male fitting is a female fitting, not shown, which is part of the quick disconnect and which is connected to suitable tubing and introduced to an on-off valve 28 which is controlled by a user of the system. An inlet check valve is connected to the on-off valve 28 which conducts the hydrazine to the gas generator 29. The output of the gas generator is connected through an exhaust check valve 30 to an outlet port 31 which is in communication with the open portion ofthe main lifting unit 23.

Incorporated in one side ofthe cylindrical portion 23 is the venting mechanism comprising a zipper 32 which incorporates a pull mechanism 33 having a central hole therein. As the zipper pull mechanism 33 is moved toward and away from the lifting eye 26 the gas level, that is assuming that the lifting eye 26 is in an upper position, is caused to vary, thereby varying the degree of buoyancy. The zipper on both sides of the pull mechanism 33 is closed so that the only vent to ambient pressure is through the pull mechanism 33.

All metal parts of the operating mechanism are formed of stainless steel which is compatible with the salt water environment. As previously stated, the end portions of the lifting mechanism, that is 20 and 21, are formed of polyurethane while the outer shell 22 and 23 is formed of Fiberglas.

In operation, the bellows expulsion unit [0 is filled with hydrazine at a shore facility. The procedure for filling involves collapsing the bellows 35, installing the male half of a quick disconnect. then connecting the mating half of the fuel quick disconnect which is attached to a flexible line from a pressurized hydrazine source to the bellows. The bellows is then filled with, in the present instance, I27 cubic inches of hydrazine fuel at approximately 5 p.s.i. Any number ofexpulsion bellows could then be packed in a container and delivered to the salvage support ship and stored until needed.

When the salvage ship is on a salvage site and in preparation for an operation, the bellows 35 is removed from the container and inserted into the spring-loaded expulsion unit l0. This is accomplished using a loading procedure similar to that described wherein the spring 11 is compressed, the bellows retainer plate 13 removed, the expulsion bellows inserted and the bellows-retaining plate replaced. The loading screw 15 is then removed and the fuel expulsion bellows allowed to absorb a load produced by the compressed spring ll acting upon it.

The monopropellant gas generator assembly 29 with the mating half of the quick disconnect on the fuel feedline is then mated to the fuel expulsion unit with the hand-controlled valve 28 closed. The entire monopropellant gas generator unit is then mounted in the diver-controlled buoyancy system on end portion 20 and the system lowered over the side of the ship to the divers.

Upon completing a mission, the divers close the hand control valve 28 and return the system to the surface support ship. The gas generator assembly is then removed by parting the quick disconnect, the loading screw islattached to the piston to allow removal of the hydrazine fuel'expulsion bellows and the empty or partially empty fuel expulsion bellows is then stored for future refilling.

The preferred embodiment of the invention has been described using a hydrazine gas generator. This generator would be preferred when working at saturation depths. i.e., over feet. However, at lesser depths one might use other gas-producing means, for instance, CO generator, air bottle, etc., in place ofthe hydrazine gas generator.

What is claimed is:

l. A buoyancy system comprising:

a lifting assembly having spaced-apart end portions;

an essentially gas-impermeable section connecting said end portions and defining an enclosed space;

gas supply means for supplying gas to said enclosed space;

venting means in said gas-impermeable section for adjusting the amount of buoyancy in the system; and said venting means being located in the wall of said gas-impermeable section, and being slidably adjustable so that a very tine adjustment of the buoyancy of said buoyancy system can be made.

2. A prepackaged buoyancy system as set forth in claim I, wherein said fuel supply means comprises a cylindrical container having a replaceable fuel element.

3. A prepackaged buoyancy system as set forth in claim I and further including venting means in said gas-impermeable section for adjusting the amount of buoyancy in the system.

4. A prepackaged buoyancy system as set forth in claim 3 wherein said venting means is slidably adjustable the entire length of ration.

said gas-impermeable section. 8. A prepackaged buoyancy system as set forth in claim I 5. A prepackaged buoyancy system as set forth in claim 2 wherein and further including spring-biasing means in physical ntact said venting lneans comprises a slide fastener and a pull with said fuel element for expelling said fuel through said gas 5 lllek-hlmifimgenerator means on demand. 9. A prepackaged buoyancy system as set forth in claim 8 6. A prepackaged buoyancy system as set forth in claim 2 Whckl" wherein said slide fastener is closed at all portions exterior to said pull mechanism and open at portions interior to said pull l0 mechanism; and

said pull mechanism has a hole therein which allows open communication, through said slide fastener, between said enclosed space and said ambient pressure.

said replaceable fuel element is in pressure communication with ambient outside pressure at a portion thereof removed from the connection to said gas generator means.

7. A prepackaged buoyancy system as set forth in claim 2 wherein said replaceable fuel element is of a bellows eonfigu 

1. A buoyancy system comprising: a lifting assembly having spaced-apart end portions; an essentially gas-impermeable section connecting said end portions and defining an enclosed space; gas supply means for supplying gas to said enclosed space; venting means in said gas-impermeable section for adjusting the amount of buoyancy in the system; and said venting means being located in the wall of said gas-impermeable section, and being slidably adjustable so that a very fine adjustment of the buoyancy of said buoyancy system can be made.
 2. A prepackaged buoyancy system as set forth in claim 1, wherein said fuel supply means comprises a cylindrical container having a replaceable fuel element.
 3. A prepackaged buoyancy system as set forth in claim 1 and further including venting means in said gas-impermeable section for adjusting the amount of buoyancy in the system.
 4. A prepackaged buoyancy system as set forth in claim 3 wherein said venting means is slidably adjustable the entire length of said gas-impermeable section.
 5. A prepackaged buoyancy system as set forth in claim 2 and further including spring-biasing means in physical contact with said fuel element for expelling said fuel through said gas generator means on demand.
 6. A prepackaged buoyancy system as set forth in claim 2 wherein said replaceable fuel element is in pressure communication with ambient outside pressure at a portion thereof removed from the connection to said gas generator means.
 7. A prepackaged buoyancy system as set forth in claim 2 wherein said replaceable fuel element is of a bellows configuration.
 8. A prepackaged buoyancy system as set forth in claim 1 wherein said venting means comprises a slide fastener and a pull mechanism.
 9. A prepackaged buoyancy system as set forth in claim 8 wherein said slide fastener is closed at all portions exterior to said pull mechanism and open at portions interior to said pull mechanism; and said pull mechanism has a hole therein which allows open communication, through said slide fastener, between said enclosed space and said ambient pressure. 